Lygus Bug Control Research Articles

Developing lygus bug control strategies in potatoes: plant variety, vertical distribution effect, and insecticide efficacy studies.

The Columbia Basin of Oregon and Washington is one of the most productive potatoes, Solanum tuberosum L., growing regions in the United States affected by numerous insect pests. Lygus bugs, Lygus spp. (Hemiptera: Miridae), are an increasing problem in potatoes. In 2015, after an outbreak of lygus bugs in potatoes in the Columbia Basin, potato producers used multiple applications of insecticides to control lygus bugs. However, it is poorly researched whether lygus bugs can cause economic damage to the crop. Therefore, our objectives were (i) to determine lygus bugs presence in potato plants, (ii) to determine damage on most commonly grown potato varieties (e.g., Alturas Russet, Ranger Russet, Umatilla Russet, Russet Burbank, and Clearwater Russet), (iii) to determine the number of insecticide applications needed to control lygus bugs, and (iv) to estimate the relationship between lygus bug density and potato yield loss. This study demonstrated that the lygus complex is widely present in the Columbia Basin, Lygus spp. prefers the upper 1/3 section of potato plants in all varieties tested, and the number of applications throughout a field season does not affect yield regardless of variety.

EVALUATING INSECTICIDES FOR CONTROL OF ADULT LYGUS BUGS (MIRIDAE: HEMIPTERA) IN CALIFORNIA STRAWBERRIES

A centrifuge tube bioassay (CTB) method was developed to screen candidate products for the control of lygus bugs in strawberries before conducting field-scale testing. To evaluate the CTB method, results of a CTB and a strawberry field trial in Watsonville, California were compared. Insecticides tested were Actara (thiamethoxam), Danitol (fenpropathrin), Malathion 8 Aquamul (malathion), PrevAm (sodium tetraborohydrate decahydrate), and tank mixtures. The CTB results were in agreement with field trial results for products affording direct mortality. The field trial identified the Actara and Danitol mixture as the most efficacious treatment.

Effects of <I>Beauveria bassiana</I> on <I>Lygus hesperus</I> (Hemiptera: Miridae) Feeding and Oviposition

Effects of Beauveria bassiana (Balsamo) Vuillemin infection on feeding and ovipositional behavior of Lygus hesperus Knight were investigated in the laboratory. In the feeding experiment, bugs were inoculated with different concentrations (LC10, LC50, LC90) of B. bassiana conidia and feeding damage was measured on flower buds of Wisconsin fast plants, Brassica rapa L., after 5 d. We detected greater feeding damage by inoculated bugs compared with noninoculated bugs, particularly bugs that died during the experiment. In the oviposition experiment, bugs were inoculated with a high concentration of conidia (LC90 at 25°C) and incubated for 6 d at 25 or 35°C, temperatures that are optimal and suboptimal, respectively, for B. bassiana growth. Most inoculated bugs died at 25°C but survived at 35°C during the 6-d experiment. Incubation temperature did not significantly affect L. hesperus oviposition. B. bassiana inoculation reduced the oviposition rate of lygus bug, particularly in bugs that did not show sporulation at the end of the experiment. If B. bassiana is used for lygus bug control in seed crop fields, the behavioral changes of infected bugs are unlikely to contribute to a reduction in seed damage.

Vacuums provide limited Lygus control in strawberries

Lygus bug (Lygus hesperus) feeding causes small strawberry size and weight, but the most serious damage is a deformation of the fruit called “cat-facing.” Over two growing seasons, three grower-designed vacuum machines were evaluated for season-long control of Lygus bugs in production strawberry (var. ‘Selva’) fields on the coast. The Lygus bug control in fields vacuumed weekly and twice-weekly was compared to that in fields treated with malathion insecticide or an unregistered pesticide, bifenthrin. All vacuum machines significantly reduced Lygus bug damage when compared to the untreated control. However, the damage in plots treated only with the vacuum machines was high enough to be considered economically unacceptable.

Evaluation of Insecticides for Lygus Bug Control, 1987

Abstract White lupin was seeded in experimental plots at 200 lb/acre in 11-inch rows near Waitsburg, Walla Walla County, Wash., for the control of lygus bugs. Seven treatments were replicated 4 times in a randomized complete block design of 0.01-acre plots. The treatments were applied with a CO2-powered backpack sprayer with a 4-ft spray boom calibrated to deliver 27 gal/acre at 30 psi. Four 8003 flat-fan nozzles at 19-inch spacings were used on the spray boom. First treatment was on 8 Jun at 50% primary bloom; the second treatment was made on 20 Jun. A third, late-season treatment was applied on 20 Jul. Population densities of lygus bugs were determined from 5 (180-degree) sweeps with a 15-inch-diam sweep net on 8, 14, 20, and 28 Jun and 8, 16, and 28 Jul. Samples were bagged in the field and counted in the laboratory. Adult lygus bugs (ALB) were counted separately from nymphs (NLB).

Lygus Bug Control on Cotton, 1983

Abstract Two applications of insecticides for lygus bug control were made on Acala SJ-2 cotton planted 16 April at the Univ. of California West Side Field St. (Five Points, Fresno County, Calif.). Individual plots were 24 rows wide (40-in centers) and 150 ft long, replicated four tmes in a randomized complete block design. All treatments were made with a high clearance ground sprayer (Hagie 470) equipped with drop booms, through five nozzles per row delivering 25 gal/acre at 40 lb/in2 . Application dates were 2 to 3 Aug. and 29 to 30 Aug. (Zectran at 0.25 lb (AI)/acre was not retreated). On 17 Aug. an application of Comite 6.5E at 1.4 lb (AI)/acre was made toan eight-row subplot in each plot; insect and mite counts were not made in these subplots although yield was recorded. Sweep net (lygus bugs) and D-Vac (lygus bugs and predators) samples were taken 1, 6, 14, 21, 30, and 35 days posttreatment. Spider mite counts were made on 17 Aug. and 1 Sept. by sampling 100 mainstem leaves (eighth unfolded leaf below terminal) per treatment (25 per replicate) and processing through a sodium hypochlorite wash system. Yields were determined by mechanical harvest of the center four rows of each subplot. Sweep net samples 1 day pretreatment averaged 22.5 L. hesperus per 50 net sweeps.

Control of Lygus Bugs on Carrot Seed Crops with Temik, 1979

Abstract ‘Chantenay Red Core’ carrots grown for seed in Shano silt loam (XerolIic Camborthids) soil near Hermiston, OR, were sidedressed with Temik at the time of bolting. The granules were injected 3 inches into the soil 5 inches from the plant row on May 16. The plots were rill irrigated within one week of the application. Each of the 4 replications in the randomized complete block design consisted of a plot 12 rows wide by 50 ft long. The rows were 22- and the plants 6 inches apart. Efficacy was determined by counting the number of lygus in 10-sweep samples/plot taken each week from Jun 6 through Jul 30. Phytotoxicity was determined by counting the number of plants in 8, 5-ft row sections in each plot at harvest on Jut 30. The weight and percentage germination of 100-seed subsamples from these same sections was recorded also. The seeds were germinated on moist filter paper in petri dishes in a controlled environment.

Control of Lygus Bugs on Carrot Seed Crops with Temik, 1978

Abstract ‘Chantenay Red Core’ carrots grown for seed in Ephrata sandy loam (Xerollic Camborthids) soil near Quincy, WA, were sidedressed with Temik at the time of bolting. The granules were injected 3 inches into the soil 5 inches from the plant row on May 22. The plots were rill irrigated within 1 week of the application. Each of the 3 replications in the randomized complete block design consisted of a plot 12 rows wide by 50 ft long. The rows were 22-and the plants 6-12 inches apart. Efficacy was determined by counting the number of lygus in 10-sweep samples/plot at weekly intervals from Jun 1 through Aug 14. Phytotoxicity was determined by counting the number of plants in 8, 5-ft row sections in each plot at harvest on Aug 2. The weight and percentage germination of seed samples from these same sections was also recorded. Seeds were germinated on moist filter paper in petri dishes in a controlled environment.

Lygus Bug Control on Cotton, 1979 AND 1980

Abstract Single applications of insecticides for lygus bug control were made on Acala SJ-2 cotton at the University of California West Side Field Station. Individual plots were 24 rows wide 940 inch centers) and 150 ft long, replicated 4 times in a randomized complete block design. All treatments were made with a high clearance sprayer equipped with drop booms, through 5 nozzles/row delivering 25 gal/acre at 40 psi. Application dates were Jul 31, 1979 and aug 5, 1980. Sweep net (lygus bugs) and D-Vac (lygus bugs and predators) samples were taken 1.7.14 and 21 days post-treatment. Insect counts are reported as sums of the 4 post-treatment samples and were transformed by x + 0.5 for analysis. Yields were determined by mechanical harvest of the center 4 rows of each plot. Sweep net samples one day pre-treatment were 14.5 and 11.4 L. hesperus per 50 net sweeps in 1979 and 1980 respectively.

Cotton Arthropod Food Chain Disruptions by Pesticides in the San Joaquin Valley, California 1

Populations of the western flower thrips, Frankliniella occidentalis (Pergande) and 2 important predators (Geocoris pallens Stall; Orius tristicolor White) were monitored in relationship to cotton plant growth and chemical applications for lygus bug control in the San Joaquin Valley, California. F. occidentalis abundance was closely correlated with the blooming of the cotton. Reduction of G. pallens from the multiple dimethoate and naled-toxaphene applications in 1971, and from dimethoate treatments in 1972 allowed the thrips population to increase significantly. O. tristicolor was the predator most correlated with the thrips population. Predator mortality was reflected in the number of beet armyworm, Spodoptera exigua (Hübner), larvae which arose in the late season 1971 and by cabbage looper, Trichopulsia ni (Hübner), larvae in 1972. Differential crop damage due to differences in larval numbers led to 21.5% greater cotton lint yield per ha in 1971 in plots treated with naled-toxaphene in comparison to plots treated with dimethoate. In 1972, the untreated plots netted 48 and 80 more per ha than plots treated with dimethoate or aldicarb, respectively.

Field Cage Evaluation of Predators for Control of Lygus hesperus Knight on Cotton

Predator efficiency of Lygus hesperus Knight was evaluated in a series of 5 treatments: (1) Geocoris pallens (Stal), (2) Nabis americoferus Carayon, (3) Chrysopa carnea Stephens, (4) the naturally occurring predator complex, and (5) Control or check. Geocoris pallens was very effective on egg-nymph or nymph populations of lygus bugs. Nabis americoferus was effective as a predator on the egg-nymph stages when confined to sleeve cages, but ineffective in large (183 cm × 183 cm × 366 em) field cages. Chrysopa carnea was ineffective. The natural predator complex provided 53–76% control of lygus bugs in the egg-nymph state.

Systemic Insecticides as Lygus Bug Controls Compatible with Bee Pollination on Alfalfa1

Two low-bee-hazard methods of control, the use of granular insecticides and application of insecticides through a sprinkler irrigation system, were tested against Lygus Hesperus Knight and L. elisus Van Duzee in alfalfa grown for seed. Only dimethoate provided control of lygus bugs when applied through irrigation sprinklers. However, such applications at higher than normal dosage rates to blooming alfalfa apparently caused a low mortality to alfalfa leafcutting bees, Megachile rolundala (F.), by nectar contamination. Dimethoate applied after hay cutting and before development of seed crop blooms was non-hazardous to bees. Temik® (2-methyl-2- (methylthio)-propionaldehyde O-(methylcarbamoyl)oxime), Baygon® ( 0 -isopropoxyphenyl methylcarbamate), and NIA-I0242 (Furadan® (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) granules provided nearly 7 weeks control of lygus bugs at 2 to 3 lb per acre in both aerial broadcast and ground side-dressed applications. Temik at 5 lb per acre gave from nearly 7 weeks to more than 3 months control of lygus bugs and also controlled pea aphids Acyrtho siphon pisum (Harris). Granular systemic insecticides were not effective until irrigation was applied, but either sprinkler or rill irrigation sufficed. Beneficial predators either were not seriously reduced or were able to recover in time to keep aphids below economic levels. Trichlorfon performance was improved by timing the second application about 10 days after the first, killing the early lygus instars winch had hatched out in the meantime, Abate®( O,O -dimethyl phosphorothioate O,O diester with 4,4'-thiodip.henol) provided 3 weeks control of lygus bugs, but was highly toxic to the alfalfa leafcutting bee and moderately toxic to the alkali bee, Nomia melanderi Cockerell.

Field Studies on Control of Lygus Bugs and Onion Thrips Infesting Safflower1

Field tests in 1962 and 1964 on control of the lygus bug Lygus elisus (Van Duzee), and onion thrips, Thrips tabaci Lindeman, on Gila variety safflower, Carthamus tinctorius L., resulted in excellent control of both insects by dimethoate. Phosphamidon provided very effective initial control but did not give satisfactory residual activity Control was less with trichlorfon, Bay 25141 ( O, O -diethyl O -[ p -(methylsulfinyl) phenyl] phosphorothioate), carbophenothion, azinphosmethyl. endosulfan, diazinon, dieldrin, naled. carbaryl, fenthion, and Union Carbide UC 20047A ( exo -5-chloro-6-oxo- endo -2-norbornanecarbonitrile O -(methylcarbamoyl) oxime). Treatments in 1964 did not result in statistically significant seed-yield increases.

Insecticidal Control of Lygus Bugs and Effect on Yield and Grade of Lima Beans1

Excellent control of lygus bugs on lima beans was obtained for several weeks following treatment with a malathion plus toxaphene combination or with dimethoate. Malathion or naled alone also provided satisfactory lygus bug control, with shorter periods of effective residual activity than malathion plus toxaphene. Although the initial control of lygus bugs afforded by a DDT plus toxaphene combination was poorer than that given by the above treatments, this combination continued to suppress the bugs for at least 4 weeks following application. Two types of damage may be caused by the feeding of lygus bugs on lima beans in California: a reduction in yield, as measured by the number of marketable beans per plant, and pitting or scarring of the beans. Two properly timed applications of malathion plus toxaphene were found necessary to provide adequate control of both types of damage on crops to be harvested as dry limas while a single application gave adequate control of both types of damage on crops to be harvested as green limas.

New Insecticides for Lygus Bug Control on Vegetable Seed Crops

Several new pesticides and combinations thereof were applied to table beet seed plants and to carrot seed plants in performance trials against the lygus bug, Lygus hesperus Knight. Six pesticides were tested: DDT, ethion, Dylox® (dimethyl 2,2,2-trichloro-l-hydroxyethylphosphonate), Thiodan® (6,7,8,9,10,10- hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin- 3-oxide), Trithion® (S-(p-chlorophenylthio) methyl O,O -diethyl phosphorodithioate), and Di-Syston® ( O,O -diethyl S -2-(ethylthio) ethyl phosphorodithioate). These were used alone or in combinations. The natural population in small plots was augmented by three introductions resulting in an accumulated high of 23.5 bugs per plant during the tests. The trials on beets involved single sprays for eight plots; and a series of five applications for two plots. A spray containing DDT plus Dylox gave the most complete control of lygus bugs, or 78% control during a 28-day period. Thiodan plus Dylox was almost equally good. Five sprays of Di-Syston and five dustings with DDT plus Trithion, and single sprays of DDT plus Trithion or DDT alone ranked in the midrange of observed values, or 56% or 62% control. Thiodan or ethion, alone or in combination, were the least effective. All applications containing Thiodan as well as the one containing DDT plus Dylox were appreciably more toxic to the pirate bug, Orius tristicolor White, than the other test materials. DDT plus Dylox spray had no perceptible effect on ladybeetles, Hippodamia spp. but sprays containing Di-Syston (5 applications) or ethion drastically reduced their numbers. DDT plus Trithion dust (5 applications) resulted in a significant increase in numbers of aphids and ladybeetles. The five Di-Syston sprays afforded a significant reduction in the number of plants infected by beet mosaic, and reduced the grade of infection. The best treatments for control of lygus bugs also increased the average size and viability of beet seed. All but one of the treatments increased the average yield of seed per plant. Dusts applied twice by aircraft to control lygus bugs in seed carrots were, in descending order of value for lygus bug control: 10% DDT plus 5% Dylox, 3% Thiodan, 10% DDT plus 2% Trithion, and 10% DDT. Seed yield was significantly increased in third-stage seed heads by the DDT plus Trithion dust. Increa sed yield for fourth-stage seed heads was obtained only from plants dusted with DDT plus Dylox, the only treatment that gave very significant increases in seed size for seeds threshed from third- and fourth-stage seed heads.

The Effect of Lygus Bug Control on the Yield of Lima Beans1

Field tests showed that in years when the tarnished plant bug (Lygus lineolaris (P. de B.)) population was high yields of Fordhook 242 and Henderson Bush lima beans could be substantially increased in western New York through the application of insecticides. In addition, plants protected from tarnished plant bug nymphs with insecticide or by screening set more pods earlier in the season and reached maturity earlier than did unprotected plants.

Field Tests with Various Insecticides for the Control of Lygus Bugs and the Corn Earworm on Lima Beans1

In a series of replicated field tests in southern California Against lygus bugs, principally Lygus hesperus (Kngt.) and the corn earworm (Heliothis zea (Boddie)) on lima beans, the best control of lygus bugs was given by dieldrin, toxaphene, endrin, DDT-toxaphene, and DDT (mentioned in order of their effectiveness). In reducing pitting of beans caused by lygus feeding, DDT-toxaphene was the most effective. It also gave the highest yield of dry beans (4 sacks per acre more than the check), followed by dieldrin, endrin, and DDT. Endrin was the most effective material for the combined control of lygus and the corn earworm. Toxaphene, DDT-toxaphene, and DDT alone gave adequate control of both insects and were less costly than endrin. DDT is the least expensive; one application will give good control of lygus bugs if properly applied at the right time, and a second application will reduce corn earworm damage and prevent reinfestation of lygus.

Evaluation of Insecticides for Lygus Bug Control and Their Effect on Predators and Pollinators

A laboratory method involving the use of caged carrot seed heads was evolved to study the effectiveness of new insecticides and insecticidal combinations for lygus bug control. These laboratory tests showed that DDT or toxaphene combined with Dipterex or malathion resulted in quicker lygus bug mortality and lasted for a longer period of time than each insecticide did when used alone. Malathion and Dipterex alone resulted in satisfactory lygus bug control, but they were not as long lasting as DDT. Bayer 19639, Thiodan, demeton, endrin, and a combination of DDT-Trithion were identified as new treatments of potential value against this pest by means of the laboratory tests. Replicated plots and aircraft applications in fields of seed carrots showed that DDT was satisfactory for lygus bug control in this area. DDT did not appreciably reduce numbers of honeybees or cause a buildup of red spiders. Dipterex and malathion resulted in satisfactory lygus bug control, caused no spider mite buildup, but did not last as long as DDT and were of no ad- vantage for use on the carrot seed crop. Under the conditions of these experiments, DDT-Dipterex was the only new treatment indicated as a possible substitute for DDT or toxaphene for lygus bug control. This combination treatment significantly increased mortality over that of DDT, did not induce a buildup of spider mites, or reduce numbers of honeybees. The toxaphene-Dipterex combination was also significantly more toxic to lygus bugs than DDT. However, this combination, as well as toxaphene-malathion and DDT-malathion combinations, caused a spider mite buildup; and they were highly toxic to the predaceous insects present in carrots grown for seed. Data from field trials on carrot seed crops showed that it was advisable to evaluate new treatments in terms of their effect on beneficial insects as well as on the lygus bugs.

Natural Enemies of the Spotted Alfalfa Aphid in Utah1

Seven main groups of predators of the spotted alfalfa aphid were collected from alfalfa fields near Delta, Utah: Coccinellidae, Orius, Nabis, Geocoris, Collops, Chrysopa and syrphid flies. These predators fed largely on the pea aphid (Macrosiphum pisi (Harris)) until the spotted alfalfa aphid (Therioaphis maculata (Buckton)) invaded the area. The effectiveness of predators depended on the availability of host insects and climatic conditions. The coccinellids, as a group, proved to be the most effective predators. Within this group, Hippodamia convergens G.-M. was the most beneficial, numerous and widely distributed predator. The species of Orius and Collops were abundant enough in many cases to be of real importance in the control of this aphid. The predatory species, without question, exerted a considerable controlling effect on the spotted alfalfa aphid populations. The predators held the overwintered spotted alfalfa aphid population in cheek until insecticides were applied for lygus bug control. The chemical treatments of alfalfa fields had generally adverse effects on the predators. The decrease in the number of predators and favorable environmental conditions enabled aphids to build up to the point that the application of insecticides for their control became quite generally necessary. The use of chemicals produced a sudden but temporary reduction in the population of aphids.

Control of Lygus Bugs with DDT as Related to Guayule Seed Production

Control of Lygus Bugs with DDT as Related to Guayule Seed Production